2. Spread brussels sprouts in single layer on prepared pan and toss with oil. Roast in upper third of oven, stirring occasionally, 12 minutes.

3. Add onions to pan, tossing to combine, and roast until vegetables are tender and golden brown, about 10 minutes longer. Drizzle with vinegar, tossing to combine, and roast 2 minutes longer. Transfer to serving bowl and season to taste with sea salt and pepper.